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Planting the Seed (Plant Lab)

Often times when you are in a biology class, you spend your time learning about the organisms that comprise the world around you. Typically, this involves learning about animals, the human body, and the way they function both internally and in the outside world. The problem with this is that often times a crucial component to our natural world is overlooked or hardly mentioned: the plants. Every ecosystem, and therefore every animal, rely on plants one way or another. They are just as complex as any animal in the way they contribute to the world. All I have to say to biology classes is that plants are important too!

In terms of my AP Bio class, we have actually been doing an experiment that is focused solely on plants. That’s right- we’re making sure to cover all the important parts of the natural world! This plant experiment is actually one that we started in the first week of school, and has continued up until now (which, so you know, is approximately 40 days or so). The experiment involves the concept of artificial selection. This experiment involves planting different types of plants, letting them develop, cross pollinating them with another types of plant, harvesting the seeds, and then replanting the next generation. The ultimate goal is to see what kind of plants result from these combinations, which will help us express artificial selection (which is occuring, as humans are intervining to decide who receives the pollen from who).

Now, for some quick important business: This lab is still not completed. Please understand that this is an experiment that takes time. During the time this post was published, the plants have just been harvested of their seeds. The next step will be to replant the next generation. Those results, as well as a much more in-depth explanation of artificial selection and the discoveries from the lab, will be in a follow up post that will happen later this year. After all, we can only move as fast as the plants can grow!

The point of this post is to bring you all up to speed on how the experiment is going. I’m going to give you a picture representation of all of the major events that have happened since the very first day. Please take notice of how the plants develop and grow over time. Let’s take a step back in time…

The lab began on August 27th, 2012. This first picture you see is from day 4 of our experiment. Each type of seed, the type of plants they will become are Wisconsin Fast Plants, is given its own styrofoam “cube” of four growing sections. The four types of seeds used, which correspond to the labeled styrofoam in the pictures are as follows:

These cubes are sitting on a cloth pad, which extends down into the plastic container, which is full of water. (We use a precise squirt bottle to water the plants every day as well). This pad, which is constantly moist due to the water it sits in, provides a water supply for the plants as they grow. These plants are directly below growing lights, which are constantly left running.

This is from September 4th, or our ninth day of the experiment. We ended up planting too many seeds into each indivdual growing section. For the sake of the experiment, we removed some of the smaller, less developed plants (they were transplanted to another group). This is important to mention as it shows that artificial selection has already somewhat taken place. Notice the difference in the before (top) and after (bottom) pictures.

As you can see here, our plants are continuing to get taller. Toothpicks were added to provide a structure for the plants to grow around. The metal trays from under the plants were also removed- their primary purpose of bringing the plants closer to the light is no longer necessary. This is the 12th day of our lab.

On September 11th (and repeatedly up through September 14th), we had the experience of cross pollinating our plants! To make this experiment proper, we tried to keep everything as accurate as possible. So, in order to do so, we made “bee sticks”- dried bees that are glued to the end of toothpicks. These bees are then rubbed against the blossoming flowers of the two types of plants that we decided to mate. For the lab, we decided to mate Variegated and Yellow Green Leaf, and then Non-Purple Stem Hairless and Non-Purple Stem, Yellow Green Leaf. The act of making this decision is the artificial selection component of this lab. We decided to mate the Yellow Green Leaf and Variegated plants to see which leaf type is dominant, and which is recessive. We then decided to cross pollinate the other two plants (NPS H and NPS YGL) to see if it was possible to get a purple stem, or to see what other combinations might be possible (it sounds absurd, but with genetics, anything is possible!).

The “bags” you see covering some plants are protection, to ensure pollen does not spread while the other plants are pollinating with the bee sticks. Please also note the pollen on the bee, which was taken with a computer and a hi tech microscope.

Here are our plants on September 18th and 19th. This would be day 23 and 24 in our experiment. As you can see, our plants are thriving quite nicely! The green pods you see forming (yes, they look like tentacles) are the seed pods. Yellow flowers, as well as different colors/types of leaves, are also forming as each unique plant develops. They have gotten much taller, and have required longer support sticks as well.

October 2nd is when these pictures were taken. Our plants aren’t looking so good. However, this is perfectly normal! No need to worry! These plants are designed to only have a maximun life span of one month. This is about the monthly mark for this lab, and the plants are starting to die. The first signs of the decaying plants were towards the end of September. Please note the thriving seed pods (you can see their green coloration still despite the brown of the plants). They are perfectly healthy, and getting ready to be harvested.

This is the last entry for this blog post. By now, we have hit day 54or so (October 18th), and the plants have expired. On this day, we harvested the seeds. To do so, we removed the pods from the plants, and then broke them open. We then compiled the seeds into a sort of pouch, which is where they are now being stored. The seeds of the plants that were cross pollinated together were mixed together. Please take notice in the pictures of how the seed pods are divided into two compartments, with a thin film layer separating them.

This brings us to the present. Now you know where we have come from as far as this experiment. However- do not forget that we are not done yet! The next step will be to take the seeds that we have collected, and replant them the exact same way as the last group. Then, we will observe how these plants develop. We should be able to see some distinct differences, which will relate to the original parent plants’ characteristics. So for now, like the season finale of that gripping show you always watch, this experiment is to be continued…